In the first two years of the show, Pamela Anderson played the part of Tim's Tool Girl, Lisa, on Tool Time, but left the show to focus on her role on the syndicated series Baywatch. Her last episode as a series regular was "The Great Race", which aired on May 19, 1993. Tim's new assistant, Heidi, played by Debbe Dunning, replaced Anderson as the Tool Time Girl for the following third season, starting with "Maybe Baby", which aired on September 15, 1993. Anderson did reprise the role of Lisa on the sixth-season finale episode "The Kiss and the Kiss-Off", which aired on May 20, 1997.
Tool Time was conceived as a parody of the PBS home-improvement show This Old House. Tim and Al are caricatures of the two principal cast members of This Old House, host Bob Vila and master carpenter Norm Abram. Al Borland has a beard and always wears plaid shirts when taping an episode, reflecting Norm Abram's appearance on This Old House. Bob Vila appeared as a guest star on several episodes of Home Improvement, while Tim Allen and Pamela Anderson both appeared on Bob Vila's show Home Again. House Painting